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Abstract:

A method implemented in a computer infrastructure including a combination
of hardware and software includes receiving from a local computing device
a request to securely delete a file. The method also includes determining
the file is deduplicated. The method further includes determining one of:
the file is referred to by at least one other file, and the file is not
referred to by another file. The method additionally includes securely
deleting links associating the file with the local computing device
without deleting the file when the file is referred to by at least one
other file. The method also includes securely deleting the file when the
file is not referred to by another file.

Claims:

1. A method implemented in a computer infrastructure comprising a
combination of hardware and software, the method comprising: receiving
from a local computing device a request to securely delete a file;
determining the file is deduplicated; determining one of: the file is
referred to by at least one other file, and the file is not referred to
by another file; when the file is referred to by at least one other file,
securely deleting links associating the file with the local computing
device without deleting the file; and when the file is not referred to by
another file, securely deleting the file.

2. The method of claim 1, wherein the request to securely delete the file
includes a user designated secure delete algorithm.

3. The method of claim 2, further comprising comparing the user
designated secure delete algorithm to a secure delete algorithm
associated with the file.

4. The method of claim 3, wherein the comparing comprises comparing a
strength of the user designated secure delete algorithm to a strength of
the secure delete algorithm associated with the file.

5. The method of claim 4, wherein the securely deleting the links or the
securely deleting the file is performed using a stronger one of the user
designated secure delete algorithm and the secure delete algorithm
associated with the file based on the comparing.

6. The method of claim 5, wherein data identifying the secure delete
algorithm associated with the file is stored in a deduplication database
as a field associated with the file.

7. The method of claim 6, wherein: the file is referred to by at least
one other file; and the securely deleting the links comprises deleting
the links from the deduplication database.

8. The method of claim 1, wherein the file is stored by a service
provider in a cloud environment remote from the local computing device.

9. The method of claim 1, further comprising presenting a user of the
local computing device with an interface configured to permit the user to
select between preventing and permitting deduplication of the file.

10. The method of claim 1, wherein a service provider at least one of
creates, maintains, deploys and supports the computer infrastructure.

11. The method of claim 1, wherein steps of claim 1 are provided by the
service provider on a subscription, advertising, and/or fee basis.

12. A system implemented in hardware and comprising a computer
infrastructure operable to: receive, from a user, a request to securely
delete a file; determine the file is a deduplicated file by analyzing a
deduplication database; determine one of: the deduplicated file is
referred to by at least one other file, and the deduplicated file is not
referred to by another file; when the deduplicated file is referred to by
at least one other file, securely delete links associating the
deduplicated file with the user without deleting the deduplicated file;
and when the file is not referred to by another file, securely delete the
deduplicated file.

13. The system of claim 12, wherein the request to securely delete the
file includes a user designated secure delete algorithm; and further
comprising comparing a strength of the user designated secure delete
algorithm to a secure delete algorithm defined in the deduplication
database as being associated with the deduplicated file.

14. The system of claim 13, wherein the securely deleting the links or
the securely deleting the deduplicated file is performed using a stronger
one of the user designated secure delete algorithm and the secure delete
algorithm defined in the deduplication database as being associated with
the deduplicated file, based on the comparing.

15. The system of claim 14, further comprising: storing a graded list of
a plurality of secure delete algorithms in the deduplication database;
and using the graded list to perform the comparing.

16. The system of claim 14, further comprising: determining the
deduplicated file is referred to by at least one other file; determining
the user designated secure delete algorithm is stronger than the secure
delete algorithm defined in the deduplication database as being
associated with the deduplicated file; and overwriting the secure delete
algorithm defined in the deduplication database as being associated with
the deduplicated file with the user designated secure delete algorithm.

17. The system of claim 12, wherein the user is associated with a local
computing device and the file is stored in a cloud environment at a
location remote from the local computing device.

18. A computer program product comprising a computer usable tangible
storage medium having readable program code embodied in the tangible
storage medium, wherein the computer program product includes at least
one component operable to: receive a first request to securely delete a
deduplicated file, wherein the first request is received from a first
user, and the first user and a second user are linked to the deduplicated
file by data in a deduplication database; based on the first request,
securely delete data from the deduplication database linking the first
user to the deduplicated file, without deleting the deduplicated file;
receive a second request to securely delete the deduplicated file,
wherein the second request is received from the second user; and securely
delete the deduplicated file based on the second request.

19. The computer program product of claim 18, wherein: the first request
includes a first user designated secure delete algorithm; the second
request includes a second user designated secure delete algorithm; the
second request occurs after the first request; and the data deduplication
database includes a field associated with the deduplicated file and
defining an other secure delete algorithm.

20. The computer program product of claim 19, wherein the at least one
component is further operable to: compare relative strengths of the first
user designated secure delete algorithm and the other secure delete
algorithm and, based upon the comparing, perform the securely deleting
data from the deduplication database linking the first user to the
deduplicated file using a stronger one of the first user designated
secure delete algorithm and the other secure delete algorithm; and
compare relative strengths of the second user designated secure delete
algorithm and the other secure delete algorithm and, based upon the
comparing, perform the securely deleting the deduplicated file using a
stronger one of the second user designated secure delete algorithm and
the other secure delete algorithm.

21. A method of securely deleting deduplicated files in a multitenant
environment, comprising: providing a computer infrastructure being
operable to: receive a request from a user to securely delete a
deduplicated file; when more than one user is linked to the file,
securely delete data linking the user to the file without deleting the
file; and when only the user is linked to the file, securely delete the
file.

22. The method of claim 21, wherein the computer infrastructure is
further operable to: present the user with a list of a plurality of
secure delete algorithms; receive a selection of one of the plurality of
secure delete algorithms from the user; determine a stronger one of the
user selected one of the plurality of secure delete algorithms and a
secure delete algorithm associated with the file; and perform the
securely deleting the data or the securely deleting the file using the
stronger one of the user selected one of the plurality of secure delete
algorithms and the secure delete algorithm associated with the file.

23. A computer system for securely deleting deduplicated files in a
multitenant environment, the system comprising: a CPU, a computer
readable memory and a computer readable storage media; first program
instructions to receive a request from a user to securely delete a
deduplicated file; second program instructions to securely delete data
linking the user to the file without deleting the file when more than one
user is linked to the file in a deduplication database; and third program
instructions to securely delete the file when only the user is linked to
the file in the deduplication database; wherein the first, second and
third program instructions are stored on the computer readable storage
media for execution by the CPU via the computer readable memory.

24. The computer system of claim 23, wherein: the user is associated with
a local computing device; and the file is stored in a multitenant storage
environment at a location remote from the local computing device.

25. The computer system of claim 24, further comprising program
instructions to: present the user with a list of a plurality of secure
delete algorithms; receive a selection of one of the plurality of secure
delete algorithms from the user; determine a stronger one of the user
selected one of the plurality of secure delete algorithms and a secure
delete algorithm associated with the file; and perform the securely
deleting the data or the securely deleting the file using the stronger
one of the user selected one of the plurality of secure delete algorithms
and the secure delete algorithm associated with the file.

Description:

[0002] Information technology is changing rapidly and now forms an
invisible layer that increasingly touches nearly every aspect of business
and social life. An emerging computer model known as cloud computing
addresses the explosive growth of Internet-connected devices, and
complements the increasing presence of technology in today's world. Cloud
computing is a model of service delivery for enabling convenient,
on-demand network access to a shared pool of configurable computing
resources (e.g., networks, network bandwidth, servers, processing,
memory, storage, applications, virtual machines, and services) that can
be rapidly provisioned and released with minimal management effort or
interaction with a provider of the service.

[0003] Cloud computing is massively scalable, provides a superior user
experience, and is characterized by new, Internet-driven economics. In
one perspective, cloud computing involves storage and execution of
business data inside a cloud which is a mesh of inter-connected data
centers, computing units and storage systems spread across geographies.

[0004] With the advent of cloud computing, concepts such as storage clouds
have emerged. The storage clouds are a huge network of storage which can
be shared by the customers without the need for the customer to manage
the storage infrastructure. The storage cloud provider usually has a
single large storage space and the provider keeps data from all its
customers at the same place, which leads to the concept of multi-tenancy
and a multitenant environment. Usually this storage space is shared by
the entire customer base on that cloud.

[0005] When a file is deleted, typically only a file pointer is deleted
while the data blocks remain intact so there is a possibility of recovery
of this data. Secure delete is an act of securely purging the content
such that there are no remains on the storage. Secure delete is one of
the vital aspects for data security over storage. Many regulatory
compliances mandate the need for secure delete and there exits various
standards for performing secure delete. Secure purging of data at the
file level to meet secure delete requirements is the most common
approach. Some of the delete operations over a file system can be
extended to support different specifications of data remanence to
implement secure delete. Data remanence involves multiple levels of
writing with different formats depending upon the specification being
implemented.

[0006] Data deduplication comprises a process to eliminate redundant data.
In the deduplication process, duplicate data is deleted leaving only one
copy of the data to be stored. In certain embodiments, indexing of all
data is still retained should that data ever be required. Deduplication
is able to reduce the effective storage capacity because only unique data
is stored. Data deduplication can generally operate at the file or the
data block level. File level deduplication eliminates duplicate files,
but this is not a very efficient means of deduplication. Block
deduplication looks within a file and saves unique iterations of each
block or bit. Each chunk of data is processed using a hash algorithm such
as MD5 (Message-Digest Algorithm) or SHA-1 (secure hash algorithm). This
process generates a unique number for each piece which is then stored in
an index. When a file is updated, only the changed data is saved. That
is, when only a few bytes of a document or presentation are changed, only
the changed blocks or bytes are saved and the changes do not constitute
an entirely new file. Therefore, block deduplication saves more storage
space than file deduplication.

[0007] Copy-on-write (COW) is an optimization strategy used in computer
programming. The core idea is that if multiple users ask for files which
are initially the same, they can all be given pointers to the same
resource. This function can be maintained until a user tries to modify
its `copy` of the file, at which point a true private copy is created for
that user to prevent the changes becoming visible to everyone else. All
of this happens transparently to the users. The primary advantage is that
if a user never makes any modifications, no private copy need ever be
created.

[0008] It is possible in a cloud environment for a first user, e.g.,
customer A, to have a file which is deduplicated with another user, e.g.,
customer B. When customer A wants to securely delete the file, the system
tries to securely delete the file by overwriting it with random data. In
this case, deduplication uses the COW method, i.e., creating a new copy
of the file in the file system and then applying the secure delete
algorithm on this copy of the file. Effectively the original file remains
untouched and the new copy of file gets securely deleted by the secure
delete algorithm. As such, secure deletion in a multitenant environment
may not actually securely delete the original file even though the
customer believes the file is being securely deleted.

SUMMARY

[0009] In a first aspect of the invention, a method includes receiving
from a local computing device a request to securely delete a file. The
method also includes determining the file is deduplicated. The method
further includes determining one of: the file is referred to by at least
one other file, and the file is not referred to by another file. The
method additionally includes securely deleting links associating the file
with the local computing device without deleting the file when the file
is referred to by at least one other file. The method also includes
securely deleting the file when the file is not referred to by another
file.

[0010] In another aspect of the invention, a system is implemented in
hardware and includes a computer infrastructure operable to: receive,
from a user, a request to securely delete a file; determine the file is a
deduplicated file by analyzing a deduplication database; determine one
of: the deduplicated file is referred to by at least one other file, and
the deduplicated file is not referred to by another file; when the
deduplicated file is referred to by at least one other file, securely
delete links associating the deduplicated file with the user without
deleting the deduplicated file; and when the file is not referred to by
another file, securely delete the deduplicated file.

[0011] In an additional aspect of the invention, a computer program
product includes a computer usable tangible storage medium having
readable program code embodied in the tangible storage medium, the
computer program product includes at least one component operable to:
receive a first request to securely delete a deduplicated file, wherein
the first request is received from a first user, and the first user and a
second user are linked to the deduplicated file by data in a
deduplication database; based on the first request, securely delete data
from the deduplication database linking the first user to the
deduplicated file, without deleting the deduplicated file; receive a
second request to securely delete the deduplicated file, wherein the
second request is received from the second user; and securely delete the
deduplicated file based on the second request.

[0012] In a further aspect of the invention, a method of securely deleting
deduplicated files in a multitenant environment includes providing a
computer infrastructure being operable to: receive a request from a user
to securely delete a deduplicated file; when more than one user is linked
to the file, securely delete data linking the user to the file without
deleting the file; and when only the user is linked to the file, securely
delete the file.

[0013] In another aspect of the invention, a computer system for securely
deleting deduplicated files in a multitenant environment includes a CPU,
a computer readable memory and a computer readable storage media. The
system includes first program instructions to receive a request from a
user to securely delete a deduplicated file. The system includes second
program instructions to securely delete data linking the user to the file
without deleting the file when more than one user is linked to the file
in a deduplication database. The system includes third program
instructions to securely delete the file when only the user is linked to
the file in the deduplication database. The first, second, and third
program instructions are stored on the computer readable storage media
for execution by the CPU via the computer readable memory.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0014] The present invention is described in the detailed description
which follows, in reference to the noted plurality of drawings by way of
non-limiting examples of exemplary embodiments of the present invention.

[0015]FIG. 1 depicts a cloud computing node according to an embodiment of
the present invention;

[0016] FIG. 2 depicts a cloud computing environment according to an
embodiment of the present invention;

[0017] FIG. 3 depicts abstraction model layers according to an embodiment
of the present invention;

[0018] FIG. 4 depicts a data deduplication block diagram;

[0019] FIG. 5 depicts an exemplary user interface and associated
functionality in accordance with aspects of the invention; and

[0020] FIG. 6 depicts an exemplary flow diagram in accordance with aspects
of the invention.

DETAILED DESCRIPTION

[0021] The present invention generally relates to cloud computing and,
more particularly, to methods and systems for removing data remanence in
deduplicated storage clouds. Implementations of the invention provide a
secure delete mechanism usable with deduplicated files. In accordance
with aspects of the invention, the data deduplication process is enhanced
by incorporating techniques for removing data remanence, the requirements
of which often vary between users owning deduplicated data. In
embodiments, a user is permitted to selectively designate a file as
eligible or not eligible for data deduplication. In further embodiments,
data remanence is removed when one of a plurality of users referencing a
deduplicated file requests secure delete of the file. In additional
embodiments, a strongest of at least two secure delete algorithms is
determined and applied when a user requests a secure delete of a
deduplicated file.

[0022] In accordance with aspects of the invention, secure delete requests
of deduplicated files are handled based on the number of files that are
deduplicated to a master copy of the file. In embodiments, when there are
plural files (e.g., from plural users) deduplicated to a master copy and
one of the users requests a secure delete, the system securely deletes
the reference link blocks of the file associated with the user requesting
the secure delete. In this manner, the master copy is not deleted while
all links between the particular user and the file (e.g., data remanence)
are deleted, such that there is no indication that the file is (or ever
was) associated with the user requesting the secure delete. This permits
other users to keep using the deduplicated file while providing a secure
delete from the point of view of the user who requested the secure
delete. On the other hand, when there is only one user linked to a master
copy of a deduplicated file (e.g., after all other user links have been
deleted) and that user requests a secure delete, the system and method
securely deletes the master copy and all links of the user to the file.
In this manner, implementations of the invention advantageously provide a
secure delete methodology that works within the data deduplication
multi-tenant environment.

Cloud Computing

[0023] It is understood in advance that although this disclosure includes
a detailed description on cloud computing, implementation of the
teachings recited herein are not limited to a cloud computing
environment. Rather, embodiments of the present invention are capable of
being implemented in conjunction with any other type of computing
environment now known or later developed.

[0024] For convenience, the Detailed Description includes the following
definitions which have been derived from the "Draft NIST Working
Definition of Cloud Computing" by Peter Mell and Tim Grance, dated Oct.
7, 2009, which is cited in an IDS filed herewith, and a copy of which is
attached thereto.

[0025] Cloud computing is a model of service delivery for enabling
convenient, on-demand network access to a shared pool of configurable
computing resources (e.g. networks, network bandwidth, servers,
processing, memory, storage, applications, virtual machines, and
services) that can be rapidly provisioned and released with minimal
management effort or interaction with a provider of the service. This
cloud model may include at least five characteristics, at least three
service models, and at least four deployment models.

[0026] Characteristics are as follows:

[0027] On-demand self-service: a cloud consumer can unilaterally provision
computing capabilities, such as server time and network storage, as
needed automatically without requiring human interaction with the
service's provider.

[0028] Broad network access: capabilities are available over a network and
accessed through standard mechanisms that promote use by heterogeneous
thin or thick client platforms (e.g., mobile phones, laptops, and PDAs).

[0029] Resource pooling: the provider's computing resources are pooled to
serve multiple consumers using a multi-tenant model, with different
physical and virtual resources dynamically assigned and reassigned
according to demand. There is a sense of location independence in that
the consumer generally has no control or knowledge over the exact
location of the provided resources but may be able to specify location at
a higher level of abstraction (e.g., country, state, or datacenter).

[0030] Rapid elasticity: capabilities can be rapidly and elastically
provisioned, in some cases automatically, to quickly scale out and
rapidly released to quickly scale in. To the consumer, the capabilities
available for provisioning often appear to be unlimited and can be
purchased in any quantity at any time.

[0031] Measured service: cloud systems automatically control and optimize
resource use by leveraging a metering capability at some level of
abstraction appropriate to the type of service (e.g., storage,
processing, bandwidth, and active user accounts). Resource usage can be
monitored, controlled, and reported providing transparency for both the
provider and consumer of the utilized service.

[0032] Service Models are as follows:

[0033] Software as a Service (SaaS): the capability provided to the
consumer is to use the provider's applications running on a cloud
infrastructure. The applications are accessible from various client
devices through a thin client interface such as a web browser (e.g.,
web-based e-mail). The consumer does not manage or control the underlying
cloud infrastructure including network, servers, operating systems,
storage, or even individual application capabilities, with the possible
exception of limited user-specific application configuration settings.

[0034] Platform as a Service (PaaS): the capability provided to the
consumer is to deploy onto the cloud infrastructure consumer-created or
acquired applications created using programming languages and tools
supported by the provider. The consumer does not manage or control the
underlying cloud infrastructure including networks, servers, operating
systems, or storage, but has control over the deployed applications and
possibly application hosting environment configurations.

[0035] Infrastructure as a Service (IaaS): the capability provided to the
consumer is to provision processing, storage, networks, and other
fundamental computing resources where the consumer is able to deploy and
run arbitrary software, which can include operating systems and
applications. The consumer does not manage or control the underlying
cloud infrastructure but has control over operating systems, storage,
deployed applications, and possibly limited control of select networking
components (e.g., host firewalls).

[0036] Deployment Models are as follows:

[0037] Private cloud: the cloud infrastructure is operated solely for an
organization. It may be managed by the organization or a third party and
may exist on-premises or off-premises.

[0038] Community cloud: the cloud infrastructure is shared by several
organizations and supports a specific community that has shared concerns
(e.g., mission, security requirements, policy, and compliance
considerations). It may be managed by the organizations or a third party
and may exist on-premises or off-premises.

[0039] Public cloud: the cloud infrastructure is made available to the
general public or a large industry group and is owned by an organization
selling cloud services.

[0040] Hybrid cloud: the cloud infrastructure is a composition of two or
more clouds (private, community, or public) that remain unique entities
but are bound together by standardized or proprietary technology that
enables data and application portability (e.g., cloud bursting for
load-balancing between clouds).

[0041] A cloud computing environment is service oriented with a focus on
statelessness, low coupling, modularity, and semantic interoperability.
At the heart of cloud computing is an infrastructure comprising a network
of interconnected nodes.

[0042] Referring now to FIG. 1, a schematic of an example of a cloud
computing node is shown. Cloud computing node 10 is only one example of a
suitable cloud computing node and is not intended to suggest any
limitation as to the scope of use or functionality of embodiments of the
invention described herein. Regardless, cloud computing node 10 is
capable of being implemented and/or performing any of the functionality
set forth hereinabove. FIG. 1 can also represent a computing
infrastructure capable of performing and/or implementing tasks and/or
functions of the methods described herein.

[0043] In cloud computing node 10 there is a computer system/server 12,
which is operational with numerous other general purpose or special
purpose computing system environments or configurations. Examples of
well-known computing systems, environments, and/or configurations that
may be suitable for use with computer system/server 12 include, but are
not limited to, personal computer systems, server computer systems, thin
clients, thick clients, hand-held or laptop devices, multiprocessor
systems, microprocessor-based systems, set top boxes, programmable
consumer electronics, network PCs, minicomputer systems, mainframe
computer systems, and distributed cloud computing environments that
include any of the above systems or devices, and the like.

[0044] Computer system/server 12 may be described in the general context
of computer system-executable instructions, such as program modules,
being executed by a computer system. Generally, program modules may
include routines, programs, objects, components, logic, data structures,
and so on that perform particular tasks or implement particular abstract
data types. Computer system/server 12 may be practiced in distributed
cloud computing environments where tasks are performed by remote
processing devices that are linked through a communications network. In a
distributed cloud computing environment, program modules may be located
in both local and remote computer system storage media including memory
storage devices.

[0045] As shown in FIG. 1, computer system/server 12 in cloud computing
node 10 is shown in the form of a general-purpose computing device. The
components of computer system/server 12 may include, but are not limited
to, one or more processors or processing units 16, a system memory 28,
and a bus 18 that couples various system components including system
memory 28 to processor 16. In embodiments, the computer system/server 12
comprises or communicates with a deduplication/delete manager 80 as
described in greater detail herein.

[0046] Bus 18 represents one or more of any of several types of bus
structures, including a memory bus or memory controller, a peripheral
bus, an accelerated graphics port, and a processor or local bus using any
of a variety of bus architectures. By way of example, and not limitation,
such architectures include Industry Standard Architecture (ISA) bus,
Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, Video
Electronics Standards Association (VESA) local bus, and Peripheral
Component Interconnects (PCI) bus.

[0047] Computer system/server 12 typically includes a variety of computer
system readable media. Such media may be any available media that is
accessible by computer system/server 12, and it includes both volatile
and non-volatile media, removable and non-removable media.

[0048] System memory 28 can include computer system readable media in the
form of volatile memory, such as random access memory (RAM) 30 and/or
cache memory 32. Computer system/server 12 may further include other
removable/non-removable, volatile/non-volatile computer system storage
media. By way of example only, storage system 34 can be provided for
reading from and writing to a non-removable, non-volatile magnetic media
(not shown and typically called a "hard drive"). Although not shown, a
magnetic disk drive for reading from and writing to a removable,
non-volatile magnetic disk (e.g., a "floppy disk"), and an optical disk
drive for reading from or writing to a removable, non-volatile optical
disk such as a CD-ROM, DVD-ROM or other optical media can be provided. In
such instances, each can be connected to bus 18 by one or more data media
interfaces. As will be further depicted and described below, memory 28
may include at least one program product having a set (e.g., at least
one) of program modules that are configured to carry out the functions of
embodiments of the invention.

[0049] Program/utility 40, having a set (at least one) of program modules
42, may be stored in memory 28 by way of example, and not limitation, as
well as an operating system, one or more application programs, other
program modules, and program data. Each of the operating system, one or
more application programs, other program modules, and program data or
some combination thereof, may include an implementation of a networking
environment. Program modules 42 generally carry out the functions and/or
methodologies of embodiments of the invention as described herein. For
example, some or all of the functions of the deduplication/delete manager
80 may be implemented as one or more of the program modules 42.
Additionally, the deduplication/delete manager 80 may be implemented as
separate dedicated processors or a single or several processors to
provide the functionality described herein. In embodiments, the
deduplication/delete manager 80 performs one or more of the processes
described herein, including but not limited to: permit a user to
selectively designate as file as eligible (or not eligible) for data
deduplication; perform data deduplication processes; securely delete user
links (e.g., removing data remanence) to a deduplicated file when a user
requests a secure delete of the file when the master copy of the file is
referenced by other users; securely delete a master copy of a
deduplicated file when the last linked user requests a secure delete; and
determine and apply a stronger one of at least two secure delete
algorithms when a secure delete is requested.

[0050] Computer system/server 12 may also communicate with one or more
external devices 14 such as a keyboard, a pointing device, a display 24,
etc.; one or more devices that enable a user to interact with computer
system/server 12; and/or any devices (e.g., network card, modem, etc.)
that enable computer system/server 12 to communicate with one or more
other computing devices. Such communication can occur via I/O interfaces
22. Still yet, computer system/server 12 can communicate with one or more
networks such as a local area network (LAN), a general wide area network
(WAN), and/or a public network (e.g., the Internet) via network adapter
20. As depicted, network adapter 20 communicates with the other
components of computer system/server 12 via bus 18. It should be
understood that although not shown, other hardware and/or software
components could be used in conjunction with computer system/server 12.
Examples, include, but are not limited to: microcode, device drivers,
redundant processing units, external disk drive arrays, RAID (redundant
array of inexpensive disks or redundant array of independent disks)
systems, tape drives, and data archival storage systems, etc.

[0051] Referring now to FIG. 2, illustrative cloud computing environment
50 is depicted. As shown, cloud computing environment 50 comprises one or
more cloud computing nodes 10 with which local computing devices used by
cloud consumers, such as, for example, personal digital assistant (PDA)
or cellular telephone 54A, desktop computer 54B, laptop computer 54C,
and/or automobile computer system 54N may communicate. Nodes 10 may
communicate with one another. They may be grouped (not shown) physically
or virtually, in one or more networks, such as Private, Community,
Public, or Hybrid clouds as described hereinabove, or a combination
thereof. This allows cloud computing environment 50 to offer
infrastructure, platforms and/or software as services for which a cloud
consumer does not need to maintain resources on a local computing device.
It is understood that the types of computing devices 54A-N shown in FIG.
2 are intended to be illustrative only and that computing nodes 10 and
cloud computing environment 50 can communicate with any type of
computerized device over any type of network and/or network addressable
connection (e.g., using a web browser).

[0052] Referring now to FIG. 3, a set of functional abstraction layers
provided by cloud computing environment 50 (FIG. 2) is shown. It should
be understood in advance that the components, layers, and functions shown
in FIG. 3 are intended to be illustrative only and embodiments of the
invention are not limited thereto. As depicted, the following layers and
corresponding functions are provided:

[0055] In one example, management layer 64 may provide the functions
described below. Resource provisioning provides dynamic procurement of
computing resources and other resources that are utilized to perform
tasks within the cloud computing environment. Metering and Pricing
provide cost tracking as resources are utilized within the cloud
computing environment, and billing or invoicing for consumption of these
resources. In one example, these resources may comprise application
software licenses. Security provides identity verification for cloud
consumers and tasks, as well as protection for data and other resources.
User portal provides access to the cloud computing environment for
consumers and system administrators. Service level management provides
cloud computing resource allocation and management such that required
service levels are met. Service Level Agreement (SLA) planning and
fulfillment provide pre-arrangement for, and procurement of, cloud
computing resources for which a future requirement is anticipated in
accordance with an SLA.

[0056] Workloads layer 66 provides examples of functionality for which the
cloud computing environment may be utilized. Examples of workloads and
functions which may be provided from this layer include: mapping and
navigation; software development and lifecycle management; virtual
classroom education delivery; data analytics processing; transaction
processing; and deduplication and secure delete. In accordance with
aspects of the invention, the deduplication and secure delete
workload/function operates to perform one or more of the processes
described herein, including but not limited to: permit a user to
selectively designate as file as eligible (or not eligible) for data
deduplication; perform data deduplication processes; securely delete user
links (e.g., removing data remanence) to a deduplicated file when a user
requests a secure delete of the file when the master copy of the file is
referenced by other users; securely delete a master copy of a
deduplicated file when the last linked user requests a secure delete; and
determine and apply a stronger one of at least two secure delete
algorithms when a secure delete is requested.

[0057] As will be appreciated by one skilled in the art, aspects of the
present invention, including the deduplication/delete manager 80 and the
functionality provided therein, may be embodied as a system, method or
computer program product. Accordingly, aspects of the present invention
may take the form of an entirely hardware embodiment, an entirely
software embodiment (including firmware, resident software, micro-code,
etc.) or an embodiment combining software and hardware aspects that may
all generally be referred to herein as a "circuit," "module" or "system."
Furthermore, aspects of the present invention may take the form of a
computer program product embodied in one or more computer readable
medium(s) having computer readable program code embodied thereon.

[0058] Any combination of one or more computer readable medium(s) may be
utilized. The computer readable medium may be a computer readable signal
medium or a computer readable storage medium. A computer readable storage
medium may be, for example, but not limited to, an electronic, magnetic,
optical, electromagnetic, infrared, or semiconductor system, apparatus,
or device, or any suitable combination of the foregoing. More specific
examples (a non-exhaustive list) of the computer readable storage medium
would include the following: an electrical connection having one or more
wires, a portable computer diskette, a hard disk, a random access memory
(RAM), a read-only memory (ROM), an erasable programmable read-only
memory (EPROM or Flash memory), an optical fiber, a portable compact disc
read-only memory (CD-ROM), an optical storage device, a magnetic storage
device, or any suitable combination of the foregoing. In the context of
this document, a computer readable storage medium may be any tangible
medium that can contain or store a program for use by or in connection
with an instruction execution system, apparatus, or device.

[0059] A computer readable signal medium may include a propagated data
signal with computer readable program code embodied therein, for example,
in baseband or as part of a carrier wave. Such a propagated signal may
take any of a variety of forms, including, but not limited to,
electro-magnetic, optical, or any suitable combination thereof. A
computer readable signal medium may be any computer readable medium that
is not a computer readable storage medium and that can communicate,
propagate, or transport a program for use by or in connection with an
instruction execution system, apparatus, or device.

[0060] Program code embodied on a computer readable medium may be
transmitted using any appropriate medium, including but not limited to
wireless, wireline, optical fiber cable, RF, etc., or any suitable
combination of the foregoing.

[0061] Computer program code for carrying out operations for aspects of
the present invention may be written in any combination of one or more
programming languages, including an object oriented programming language
such as Java, Smalltalk, C++ or the like and conventional procedural
programming languages, such as the "C" programming language or similar
programming languages. The program code may execute entirely on the
user's computer, partly on the user's computer, as a stand-alone software
package, partly on the user's computer and partly on a remote computer or
entirely on the remote computer or server. In the latter scenario, the
remote computer may be connected to the user's computer through any type
of network, including a local area network (LAN) or a wide area network
(WAN), or the connection may be made to an external computer (for
example, through the Internet using an Internet Service Provider).

[0062] Aspects of the present invention are described below with reference
to flowchart illustrations and/or block diagrams of methods, apparatus
(systems) and computer program products according to embodiments of the
invention. It will be understood that each block of the flowchart
illustrations and/or block diagrams, and combinations of blocks in the
flowchart illustrations and/or block diagrams, can be implemented by
computer program instructions. These computer program instructions may be
provided to a processor of a general purpose computer, special purpose
computer, or other programmable data processing apparatus to produce a
machine, such that the instructions, which execute via the processor of
the computer or other programmable data processing apparatus, create
means for implementing the functions/acts specified in the flowchart
and/or block diagram block or blocks.

[0063] These computer program instructions may also be stored in a
computer readable medium that can direct a computer, other programmable
data processing apparatus, or other devices to function in a particular
manner, such that the instructions stored in the computer readable medium
produce an article of manufacture including instructions which implement
the function/act specified in the flowchart and/or block diagram block or
blocks.

[0064] The computer program instructions may also be loaded onto a
computer, other programmable data processing apparatus, or other devices
to cause a series of operational steps to be performed on the computer,
other programmable apparatus or other devices to produce a computer
implemented process such that the instructions which execute on the
computer or other programmable apparatus provide processes for
implementing the functions/acts specified in the flowchart and/or block
diagram block or blocks.

[0065] FIG. 4 depicts a deduplication block diagram in accordance with
aspects of the invention. In embodiments, data 75, 75' flows from one or
more local computing devices 54, 54' to a deduplication system comprising
computing node 10 and deduplication/delete manager 80. The local
computing devices 54, 54' may be one of many local computing devices
54A-N described above with respect to FIG. 2. In a block deduplication
process, the deduplication/delete manager 80 takes each block of the data
75, 75' and runs a hash algorithm that generates a unique key for each
block. The deduplication/delete manager 80 compares the unique key for
each block to keys stored in a deduplication database 85, e.g., by
looking up the unique key for each block in the deduplication database 85
to determine if the key already exists (which indicates that the
particular block of data has been previously written). When the block has
not been written previously (e.g., there is no match to the unique key in
the deduplication database 85), the deduplication/delete manager 80
writes the block to storage 90 and the unique key for the block is
written to the deduplication database 85. The storage 90 may comprise,
for example, a storage node in the cloud as depicted in FIG. 2. On the
other hand, when the block has been written previously (e.g., there is a
match to the unique key in the deduplication database 85), the
deduplication/delete manager 80 writes a pointer that points to the
location of the original copy of the block.

[0066] As depicted in FIG. 4, more than one user may be associated with a
deduplicated file. For example, first and second local computing devices
54 and 54' may both reference the deduplicated file that is saved in data
storage 90. In embodiments, data defining a link between a particular
user (e.g., local computing device 54 or 54') and a file (or one or more
blocks of the file) is stored in deduplication database 85. As described
in greater detail herein, when a deduplicated file is referenced by at
least two users (e.g., devices 54 and 54', or referred to by files
associated with the devices) and one of the users (e.g., device 54')
requests a secure delete of the file, the data in the deduplication
database 85 defining the link between the requesting user and the file is
deleted. In this manner, any data remanence associated with the
requesting user (e.g., device 54') and the deduplicated file is deleted,
such that the requesting user performs a secure delete from their point
of view. Additionally, although the requesting user is disassociated with
the file, remaining users (e.g., device 54) still have access to the
deduplicated file since the master copy of the file saved in data storage
90 is not deleted until a last remaining user requests secure deletion of
the file.

[0067] In accordance with additional aspects of the invention, the
deduplication database 85 also stores data defining a particular secure
delete algorithm associated with a deduplicated file. In embodiments, the
deduplication database 85 and/or the deduplication/delete manager 80
stores a graded list of secure delete algorithms. Any suitable secure
delete algorithms may be sued within the scope of the invention,
including conventional secure delete algorithms (e.g., the Gutmann
method, US DoD 5220.22-M, RCMP TSSIT OPS-II, etc.) and/or later developed
secure delete algorithms. For example, the relative strengths of a
plurality of secure delete algorithms may be pre-defined (e.g., using any
desired quantitative and/or qualitative measure) and stored in the graded
list of secure delete algorithms.

[0068] In embodiments, one of the graded algorithms is assigned to the
deduplicated file either automatically by the system or by a user. For
example, the deduplication/delete manager 80 may present the list to a
user when the user is saving the file, in which case the user selects one
of the algorithms from the list. In another example, the deduplication
database 85 and/or the deduplication/delete manager 80 may be programmed
to automatically assign one of the algorithms from the list to a file
based on any combination of parameters, such as: file type, file
extension, user identity (e.g., MAC address, IP address, username, etc.),
etc. In either event, the deduplication/delete manager 80 saves data
defining the secure delete algorithm associated with the file in the
deduplication database 85, e.g., as a field associated with the file in
the deduplication database 85.

[0069] In embodiments, when a user requests a secure delete of a
deduplicated file, the user may also designate a secure delete algorithm
to use in the secure delete process. The user-designated secure delete
algorithm may be from the same graded list that is saved at the
deduplication database 85 and/or the deduplication/delete manager 80. The
user designation may be automatic (e.g., pre-defined and saved for this
user) or user-selected (e.g., from a list presented to the user by the
deduplication/delete manager 80 at the time of the request for secure
delete). In embodiments, upon receiving the request for secure delete,
the deduplication/delete manager 80 compares the user-designated secure
delete algorithm to the secure delete algorithm defined in the
deduplication database 85 as associated with the file, and uses the
stronger of the two secure delete algorithms for performing the requested
secure delete.

[0070] FIG. 5 depicts an exemplary user interface 100 and associated
functionality in accordance with aspects of the invention. In
embodiments, the interface 100 includes a properties window 110 that is
presented on a local computing device, e.g., local computing device 54.
The interface 100 may be presented on the local computing device in
response to the user performing a prescribed pattern of mouse clicks,
keystrokes, touch-screen selections, etc. As but one of many possible
examples, the interface 100 may be presented when the user selects an
existing file, right-clicks the mouse pointer on the selected file, and
selects "Properties" from a menu. Additionally or alternatively, the
interface 100 may be automatically presented to the user on the local
computing device when a file is being saved.

[0071] According to aspects of the invention, the interface 100 comprises
a deduplication selection portion 115 that includes at least one
selectable field 125, such as a user-selectable check-box, that permits a
user to designate whether this file is eligible (or not) for data
deduplication. There are situations, such as when dealing with classified
and/or confidential material, when a user may desire to prevent a file
from being deduplicated with another file. In this manner, the interface
100 with selectable field 125 provides a user with the ability to make a
deduplication designation for any given file. In embodiments, the
deduplication designation is saved as a file attribute that can be
analyzed by the deduplication/delete manager 80 for determining whether
to apply data deduplication process to a file, e.g., as shown in FIG. 4.

[0072] The interface 100 is merely exemplary and is not intended to be the
only manner of presenting the user with the ability to selectively
designate a particular file as being either eligible or not eligible for
deduplication. Any suitable interface may be employed within the scope of
the invention for presenting such functionality to the user on the local
computing device.

Flow Diagram

[0073] FIG. 6 shows an exemplary flow for performing aspects of the
present invention. The steps of FIG. 6 may be implemented in any of the
environments of FIGS. 1-4, for example.

[0074] The flowchart and block diagrams in the Figures illustrate the
architecture, functionality, and operation of possible implementations of
systems, methods and computer program products according to various
embodiments of the present invention. In this regard, each block in the
flowchart or block diagrams may represent a module, segment, or portion
of code, which comprises one or more executable instructions for
implementing the specified logical function(s). It should also be noted
that, in some alternative implementations, the functions noted in the
block may occur out of the order noted in the figures. For example, two
blocks shown in succession may, in fact, be executed substantially
concurrently, or the blocks may sometimes be executed in the reverse
order, depending upon the functionality involved. It will also be noted
that each block of the block diagrams and/or flowchart illustration, and
combinations of blocks in the block diagrams and/or flowchart
illustration, can be implemented by special purpose hardware-based
systems that perform the specified functions or acts, or combinations of
special purpose hardware and computer instructions.

[0075] Furthermore, the invention can take the form of a computer program
product accessible from a computer-usable or computer-readable medium
providing program code for use by or in connection with a computer or any
instruction execution system. The software and/or computer program
product can be implemented in the environment of FIGS. 1-4. For the
purposes of this description, a computer-usable or computer readable
medium can be any apparatus that can contain, store, communicate,
propagate, or transport the program for use by or in connection with the
instruction execution system, apparatus, or device. The medium can be an
electronic, magnetic, optical, electromagnetic, infrared, or
semiconductor system (or apparatus or device) or a propagation medium.
Examples of a computer-readable storage medium include a semiconductor or
solid state memory, magnetic tape, a removable computer diskette, a
random access memory (RAM), a read-only memory (ROM), a rigid magnetic
disk and an optical disk. Current examples of optical disks include
compact disk-read only memory (CD-ROM), compact disc-read/write (CD-R/W)
and DVD.

[0076] FIG. 6 depicts an exemplary flow for a process in accordance with
aspects of the present invention. At step 610, a secure delete and
deduplication system (e.g., a computing device running the
deduplication/delete manager 80) receives input from the user (e.g.,
local computing device), the input comprising a request to secure delete
a file and a designation of a secure delete algorithm to use when
deleting the file. Step 610 may comprise the secure delete and
deduplication system receiving a request from a user to delete the file,
presenting the user with a list of secure delete algorithms from which to
choose, and receiving from the user a designation of the one of the list
of secure delete algorithms.

[0077] At step 615, the secure delete and deduplication system determines
whether the file requested at step 610 is deduplicated. This may be
performed, for example, by examining the deduplication database 85 for an
entry corresponding to the requested file. When it is determined at step
615 that the file is not deduplicated, then at step 620 the secure delete
and deduplication system deletes the file using the secure delete
algorithm designated in the user input from step 610. The deleting the
file may comprise at least one of: deleting the copy of the file,
deleting all pointers to the file, writing random data over the location
of the file, deleting data remanence, and any other actions prescribed by
the designated secure delete algorithm.

[0078] On the other hand, when it is determined at step 615 that the file
is deduplicated, then at step 625, the secure delete and deduplication
system determines whether the file is referred to by any other files or
users as a master copy (e.g., whether the file is linked to any other
users). In embodiments, the secure delete and deduplication system makes
this determination by analyzing data in the deduplication database to
determine whether there is a reference link with which another file or
user is pointing to the file.

[0079] The process proceeds to step 630 when it is determined at step 625
that the file requested for deletion is referred to as a master copy,
e.g., another file or user is linked to this deduplicated file. At step
630, the secure delete and deduplication system determines whether the
user designated secure delete algorithm (e.g., from step 610) is stronger
than the secure delete algorithm associated with the file (e.g., the file
algorithm as defined by data associated with the file in the
deduplication database). In embodiments, the secure delete and
deduplication system compares the relative strengths of the two secure
delete algorithms, e.g., by determining which of the two secure delete
algorithms is higher in the graded list, or by using any other suitable
predefined quantitative and/or qualitative measure of the relative
strengths of the secure delete algorithms.

[0080] When it is determined at step 630 that the user designated secure
delete algorithm (e.g., from step 610) is stronger than the file
algorithm, then at step 635, the secure delete and deduplication system
replaces the file algorithm with the user designated secure delete
algorithm. This may be performed, for example, by overwriting data in the
deduplication database defining which secure delete algorithm is
associated with the deduplicated file. The process then proceeds to step
640, where the secure delete and deduplication system securely deletes
the reference links associating the user with the file using the file
algorithm, which is now the same as the user designated secure delete
algorithm by virtue of the replacing at step 635. Alternatively, when it
is determined at step 630 that the file algorithm is stronger than the
user designated secure delete algorithm (e.g., from step 610), then the
process proceeds directly to step 640, at which point the secure delete
and deduplication system securely deletes the reference links associating
the user with the file using the file algorithm.

[0081] In accordance with aspects of the invention, the deletion of links
at step 640 comprises deleting all data in the deduplication database
that defines an association between the user requesting deletion (e.g.,
from step 610) and the deduplicated file, without deleting the master
copy of the deduplicated file. In this manner, the user requesting secure
deletion is entirely dissociated with the deduplicated file in the sense
that all links between the user and the file are deleted using the secure
delete algorithm, thus ensuring that there is no data remanence linking
the user to the deduplicated file. Thus, from the standpoint of the user
requesting deletion, a secure delete has been performed. However, the
master copy of the file is not deleted since one or more other files or
users are still referencing the deduplicated file.

[0082] Referring back to step 625, when the file requested for deletion is
not referred to by any other users as a master copy, then it can be said
that the user requesting deletion is the only user linked to the
deduplicated file, and the process proceeds to step 645. This may be the
case, for example, where one or more other users have already securely
deleted their links to the deduplicated file (e.g., via step 640),
leaving the user now requesting deletion as the sole user still linked to
the deduplicated file.

[0083] At step 645, the secure delete and deduplication system determines
whether the secure delete algorithm designated by the user requesting the
secure delete (e.g., from step 610) is stronger than the file algorithm
(e.g., as defined in the deduplication database for this particular
file). This may be performed in a manner similar to step 630. When the
user designated secure delete algorithm is stronger than the file
algorithm, then at step 650 the system employs the user designated secure
delete algorithm to securely delete the file (e.g., from data storage 90)
and all links of the user to the file in the deduplication database
(e.g., similar to step 640). On the other hand, when the file algorithm
is stronger than the user designated secure delete algorithm, then at
step 655 the system employs the file algorithm to securely delete the
file (e.g., from data storage 90) and all links of the user to the file
in the deduplication database (e.g., similar to step 640). In this
manner, the master copy of the file and all data remanence are securely
deleted.

[0084] In embodiments, a service provider, such as a Solution Integrator,
could offer to perform the processes described herein. In this case, the
service provider can create, maintain, deploy, support, etc., the
computer infrastructure that performs the process steps of the invention
for one or more customers. These customers may be, for example, any
business that uses technology and provides or utilizes services. In
return, the service provider can receive payment from the customer(s)
under a subscription and/or fee agreement and/or the service provider can
receive payment from the sale of advertising content to one or more third
parties.

[0085] The descriptions of the various embodiments of the present
invention have been presented for purposes of illustration, but are not
intended to be exhaustive or limited to the embodiments disclosed. Many
modifications and variations will be apparent to those of ordinary skill
in the art without departing from the scope and spirit of the described
embodiments. The terminology used herein was chosen to best explain the
principles of the embodiments, the practical application or technical
improvement over technologies found in the marketplace, or to enable
others of ordinary skill in the art to understand the embodiments
disclosed herein. Many modifications and variations will be apparent to
those of ordinary skill in the art without departing from the scope and
spirit of the invention. The corresponding structures, materials, acts,
and equivalents of all means or step plus function elements in the
claims, if applicable, are intended to include any structure, material,
or act for performing the function in combination with other claimed
elements as specifically claimed. Accordingly, while the invention has
been described in terms of embodiments, those of skill in the art will
recognize that the invention can be practiced with modifications and in
the spirit and scope of the appended claims.